Dynamic sharing of ofdma and atdma signals

ABSTRACT

The techniques described herein relate to methods, apparatus, and computer readable media configured to decode modulated data. A modulated signal is received. A format of the modulated signal is determined, wherein the format can include a first format comprising a first type of modulated signal, or a second format comprising the first type of modulated signal and a second type of modulated signal that is different than the first type. The modulated signal is decoded by determining a frequency shift amount based on the format of the modulated signal, shifting a frequency band of the first type of modulated signal from an original position to a shifted position, thereby shifting a center frequency of the first type of modulated signal by the frequency shift amount, and filtering, based on the format of the modulated signal, signals outside of the frequency band of the shifted first type of modulated signal.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 62/468,713, entitled “DYNAMIC SHARINGOF OFDMA AND ATDMA SIGNALS” filed on Mar. 8, 2017, which is hereinincorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to dynamic sharing of OrthogonalFrequency-Division Multiple Access (OFDMA) and Advanced Time DivisionMultiple Access (ATDMA) signals, and in particular the implementation oforthogonal frequency division multiplexing (OFDM) technology for cableupstream data transfer in Data Over Cable Service InterfaceSpecification (DOCSIS).

BACKGROUND

Various standards are used in the industry for cable data transfer. Forexample, DOCSIS 3.1 is the new standard for Data-Over-Cable Service andthe first to implement OFDM technology for cable upstream data transfer.Legacy Advanced Time Division Multiple Access (ATDMA) signals underDOCSIS 3.0 may remain deployed in the same cable plants for a very longtime. The frequency band allowed for upstream is very limited. If afixed bandwidth for Orthogonal Frequency-Division Multiple Access(OFDMA) is assigned in the early stages of deployment, such an OFDMAfrequency band may be wasted if there are few DOCSIS 3.1 users. In thelater stages of deployment, the ATDMA frequency band may be wasted ifmost of the users have moved to DOCSIS 3.1 modems.

In order to achieve better efficiency, ATDMA/OFDMA bands can bescheduled dynamically. However, field tests and simulations have shownthat if the OFDMA fast Fourier transform (FFT) is performed on thecombined signals, the ATDMA signal may have significant spectral spreadon each side of it in the frequency domain due to a rectangular windowfunction applied to OFDMA FFT. This can make a region on each side ofthe ATDMA signal unusable for OFDMA carriers. Some proposed approachesuse extra band-pass filters to get the expected signal and narrow theguard band, but none of them change the mixer frequency to move theexpected signal to the center of baseband dynamically.

SUMMARY

In accordance with the disclosed subject matter, apparatus, systems, andmethods are provided for decoder-side motion vector restorationtechniques that improve the execution speed and efficiency ofdecoder-side motion vector refinement techniques.

Some embodiments relate to a decoding method for decoding modulateddata. The method includes receiving a modulated signal, determining aformat of the modulated signal, wherein the format comprises either afirst format comprising a first type of modulated signal, or a secondformat comprising the first type of modulated signal and a second typeof modulated signal that is different than the first type, and decodingthe modulated signal. Decoding includes determining a frequency shiftamount based on the format of the modulated signal, shifting a frequencyband of the first type of modulated signal from an original position toa shifted position, thereby shifting a center frequency of the firsttype of modulated signal by the frequency shift amount, and filtering,based on the format of the modulated signal, signals outside of thefrequency band of the shifted first type of modulated signal.

In some examples, filtering includes determining a set of filteringcoefficients for the modulated signal based on whether the modulatedsignal comprises the first format or the second format, and filteringthe modulated signal using the set of filtering coefficients. The methodcan include transforming the shifted first type of modulated signal fromthe frequency domain, equalizing the transformed first type of modulatedsignal to generate an equalized signal, and shifting the equalizedsignal back to the original position.

In some examples, the first type of signal comprises an OrthogonalFrequency-Division Multiple Access (OFDMA) signal, and the second typeof data comprises Advanced Time Division Multiple Access (ATDMA) signal.Determining whether the modulated signal comprises the first format orthe second format includes receiving scheduling information from ascheduler, and determining, using the scheduling information, whetherthe modulated signal comprises the first format or the second format.The modulated signal can be received on a frame-by-frame basis. Decodingthe modulated signal can include determining, for each frame, whetherthe frame comprises the first format or the second format, and decodingeach frame based on the determination, thereby allowing each framedynamically change between the first format and the second format.

Some embodiments relate to an apparatus for decoding modulated data. Theapparatus includes a receiver configured to receive a modulated signal.The apparatus includes a decoder with a mixer and a filter. The decoderis configured to determine a format of the modulated signal, wherein theformat comprises either a first format comprising a first type ofmodulated signal, or a second format comprising the first type ofmodulated signal and a second type of modulated signal that is differentthan the first type. The decoder decodes the modulated signal, includingdetermining a frequency shift amount based on the format of themodulated signal, shifting, using a mixer, a frequency band of the firsttype of modulated signal from an original position to a shiftedposition, thereby shifting a center frequency of the first type ofmodulated signal by the frequency shift amount, and filtering, using afilter that takes into account the format of the modulated signal,signals outside of the frequency band of the shifted first type ofmodulated signal.

In some examples, the decoder is configured to perform the filtering bydetermining a set of filtering coefficients for the modulated signalbased on whether the modulated signal comprises the first format or thesecond format, and filtering, using the filter, the modulated signalusing the set of filtering coefficients. The decoder can include a fastFourier transform (FFT) module configured to transform the shifted firsttype of modulated signal from the frequency domain, an equalizer incommunication with the FFT module, configured to equalize thetransformed first type of modulated signal to generate an equalizedsignal, and a shift register in communication with the equalizerconfigured to shift the equalized signal back to the original position.

In some examples, the first type of signal comprises an OrthogonalFrequency-Division Multiple Access (OFDMA) signal, and the second typeof data comprises Advanced Time Division Multiple Access (ATDMA) signal.The receiver can be configured to determine whether the modulated signalcomprises the first format or the second format by receiving schedulinginformation from a scheduler, and determining, using the schedulinginformation, whether the modulated signal comprises the first format orthe second format. The receiver can receive the modulated signal on aframe-by-frame basis, and the decoder can be configured to decode themodulated signal by determining, for each frame, whether the framecomprises the first format or the second format, and to decode eachframe based on the determination, thereby allowing each framedynamically change between the first format and the second format.

There has thus been outlined, rather broadly, the features of thedisclosed subject matter in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the disclosed subject matter that will bedescribed hereinafter and which will form the subject matter of theclaims appended hereto. It is to be understood that the phraseology andterminology employed herein are for the purpose of description andshould not be regarded as limiting.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings, each identical or nearly identical component that isillustrated in various figures is represented by a like referencecharacter. For purposes of clarity, not every component may be labeledin every drawing. The drawings are not necessarily drawn to scale, withemphasis instead being placed on illustrating various aspects of thetechniques and devices described herein.

FIG. 1 shows a typical ATDMA and OFDMA combined signals in the frequencydomain.

FIG. 2 shows typical OFDMA signals in the frequency domain when theentire frequency band is assigned to the OFDMA.

FIG. 3 shows a clean OFDMA signal after applying a bandpass filter onthe combined signal from FIG. 1.

FIG. 4 shows an exemplary ATDMA and OFDMA receiver system.

FIG. 5 shows an exemplary OFDMA receiver system, according to someembodiments.

FIG. 6 shows an OFMDA-only signal, according to some embodiments.

FIG. 7 shows an OFDMA and ATDMA combined signal, according to someembodiments.

DESCRIPTION

The inventors have recognized and appreciated that various techniquescan be used to improve dynamically sharing OFDMA and ATDMA signals. Asdescribed further herein, techniques are provided for dynamicallydecoding OFDMA signals based on the format of the modulated data (e.g.,pure OFDMA, or OFDMA and ATDMA). A frequency shift is determined basedon the format of the modulated data, and used to shift the centerfrequency of the OFDMA signal. The OFDMA signal is filtered usingfiltering coefficients that are determined based on the format of themodulated data to remove signals outside of the OFDMA signal.

For example, from the cable modem termination system (CMTS) point ofview, when OFDMA (DOCSIS 3.1) and ATDMA (e.g., DOCSIS 3.0 and/or olderversions) signals share the plant at the same time, the CMTS processesthese signals at same time. To reduce the interference in the OFDMAchannel, a large exclusion zone and several filters are typically used.In some embodiments, the techniques described herein are based on asingle symmetric finite impulse response (FIR) filter with two sets offilter coefficients for the OFDMA signal (instead of a 96 MHz bandwidthstandard OFDMA filter). When ATDMA signals are not scheduled, the entirefrequency band can be used by the OFDMA signal. In this case, the widerband filter coefficients are applied. When ATMDA signals are present,the OFDMA signal can only use part of the frequency band. In this case,the narrow band filter coefficients are applied. The switch can bescheduled at each OFMDA frame boundary on the fly. Instead of moving thecenter of the entire 96 MHz OFMDA frequency band to baseband as in thegeneral case, the center of only the active OFDMA frequency range ismoved to baseband. This can allow a simple FIR filter with symmetriccoefficients to be used instead of a complex band-pass filter ormultiple filters. This can also allow the CMTS to dynamically adjust tosignals (e.g., combined OFDMA and ATDMA signals, or OFDMA across theentire frequency band) as they are received by the CMTS on aframe-by-frame basis, e.g., rather than the CMTS needing to reset eachtime the signal changes. These and other techniques disclosed herein cansimplify the integration of DOCSIS 3.1 into existing DOCSIS (e.g., 3.0or other versions) cable plants and can also improve the utilizationrate of the frequency band and reduce system complexity.

FIG. 1 shows a typical example of ATDMA and OFDMA combined signals inthe frequency domain, according to some examples. OFDMA signals 101transmit data in each sub-carrier (not shown). The OFDMA bandwidth canbe very flexible. For example, OFDMA bandwidth can be as small as 400KHz or can be as large as 96 MHz. ATDMA signals 102A-102E (collectivelyreferred to herein as ATDMA signals 102) transmit data using singlecarrier based quadrature amplitude modulation (QAM). The centerfrequency 104 for OFDMA can be, for example, 52 MHz. The total bandwidthis the 96 MHz OFDMA band 105. The CMTS typically needs to use differenttechnologies to process ATDMA and OFDMA signals at the same time torecover data.

FIG. 2 shows the typical OFDMA signals in the frequency domain when theentire frequency band is assigned to the OFDMA signal 111, according tosome examples. In this nonlimiting embodiment, compared to FIG. 1, theOFDMA signal 111 occupies a larger frequency band (e.g., 5 MHz to 65MHz) compared to the OFDMA signal 101 frequency band (e.g., 30 MHz to 55MHz).

FIG. 3 shows a clean OFDMA signal after properly applying a bandpassfilter on the combined signal from FIG. 1, according to some examples.The filter removes the ATDMA signals 102 to produce just OFDMA signal101.

FIG. 4 depicts an ATDMA and OFDMA receiver system, according to someembodiments. The RF signal goes into a full band high-speed analog todigital converter (ADC) 301. Once the analog signal is converted to thedigital domain, the ATDMA and OFDMA signals are processed separately.FIG. 4 shows two ATDMA channel processes 400A, 400B (collectivelyreferred to as 400), which illustrate the processing flow of two ATDMAchannels through a typical ATDMA receiver system. The ATDMA receiversystem includes mixer 401, which is configured to move selected ATDMAchannels to baseband. A person of skill can appreciate that only twoprocessing flows are illustrated for exemplary purposes only. Thereceiver may perform more (or fewer) processing flows for more (orfewer) ATDMA channels. Then FIR filter 402 is applied to separate aclean ATDMA signal from the OFDMA signals and adjacent ATDMA signals.The clean ATDMA signal then goes through timing recovery and carrierrecovery 403. Time domain equalizer 404 reconstructs the QAM signal, andslicer 405 slices the data.

FIG. 4 also shows an exemplary OFDMA channel process 500 performed usingan OFDMA receiver system. The OFDMA receiver system includes mixer 501,filter 502, FFT 503, equalizer 504, and slicer 505. These components aredescribed in further detail in conjunction with FIG. 5. For illustrativepurposes, assume that the center frequency for the OFDMA cable modem isω (the center of the 96 MHz bandwidth). According to the DOCSISstandard, the center frequency ω should be the same for both CMTS andcable modem. The Mixer 501 can be configured to move the entire OFDMAchannel to baseband (96 MHz bandwidth in DOCSIS 3.1). According to someembodiments, the output sequence of the mixer 501 {Y_(Mixer) ^(n)} canbe:

Y ₅₀₁ ^(n) =X ₃₀₁ ^(n) *e ^(−iωn)  (1)

-   -   Where:    -   n is the order of ADC samples;    -   i stands for complex data;    -   {X₃₀₁ ^(n)} is the ADC input data sequence; and    -   ω is a local digital oscillator which will convert the X_(n)        signal to baseband (e.g., the OFDMA signal 101 in FIG. 1).

FIR filter 502 is applied to get a clean 96 MHz signal. In someembodiments, e.g., to obtain a smaller guard band in the combined signalcase, an additional set of band-pass filters can optionally be appliedto remove all ATDMA signals since the OFDMA signal is inside this passband. We can consider that the FIR filters just introduce a severalsample delay to sequence {Y₅₀₁ ^(n)}.

FFT module 503 converts the signal to the frequency domain. The FFTmodule 503 output is:

$\begin{matrix}{{Y_{503}^{k} = {{\sum\limits_{n = 0}^{N - 1}\; {X_{502}^{n}*e^{- \frac{i_{2\pi \; {kn}}}{N}}\mspace{14mu} {for}\mspace{14mu} k}} = 0}},1,2,\ldots \mspace{14mu},{N - 1}} & (2)\end{matrix}$

Where:

{X₅₀₂ ^(n)} is the input data sequence of FFT module 503;

N is FFT window size;

{Y₅₀₃ ^(k)} is the FFT module output sequence;

n is the order of data; and

i stands for complex data.

If we ignore sample delay in the FIR filter 502, put (1) into (2). Weget:

$\begin{matrix}{{Y_{503}^{k} = {{\sum\limits_{n = 0}^{N - 1}\; {X_{301}^{n}*e^{i\; \omega \; n}*e^{{- i}\; 2\pi \; {{kn}/N}}}} = {\sum\limits_{n = 0}^{N - 1}\; {X_{301}^{n}*e^{{- {i{({\omega + \frac{2\pi \; k}{N}})}}}n}}}}}{{k = 0},1,2,\ldots \mspace{14mu},{N - 1}}} & (3)\end{matrix}$

When local oscillator frequency

$\omega = \frac{2\pi \; m}{N}$

(m is a constant integer: 0≤m≤N−1), formula (3) changes to

$\begin{matrix}{{Y_{503}^{k} = {{\sum\limits_{n = 0}^{N - 1}\; {X_{301}^{n}*e^{{- {i{({\frac{2\pi \; m}{N} + \frac{2\pi \; k}{N}})}}}n}}} = {\sum\limits_{n = 0}^{N - 1}\; {X_{301}^{n}*e^{\frac{{- i}\; 2{\pi {({m + k})}}n}{N}}}}}}{{k = 0},1,2,\ldots \mspace{14mu},{N - 1}}} & (4)\end{matrix}$

If we apply an FFT to ADC data sequence {X₃₀₁ ^(n)} directly, we canget:

${Y_{503}^{\prime k} = {{\sum\limits_{n = 0}^{N - 1}\; {X_{301}^{n}*e^{- \frac{i\; 2\pi \; {kn}}{N}}\mspace{31mu} k}} = 0}},1,2,\ldots \mspace{14mu},{N - 1}$

Compare formula (4) and (5). If local oscillator frequency

$\omega = \frac{2\pi \; m}{N}$

(where m is a constant integer 0≤m≤N−1), then mixer 501 just shifts theFFT output sequence {Y′₅₀₃ ^(k)} by −m position to get new FFT outputsequence {Y₅₀₃ ^(k)}.

FIG. 7 is shows an OFDMA and ATDMA combined signal, according to someembodiments. If the receiver moves the OFDMA signal with additionalfrequency shift 651, the center of OFDMA signal 101 will move to DC(e.g., 0 Hz) position 660. Then one simple symmetric FIR filter 652 canbe applied to remove all ATDMA signals and out-of-band noise. If we addadditional frequency shift

$\omega^{\prime} = \frac{2\pi \; m_{N}}{N}$

(N and m_(N) are integers to make sure the frequency shift is multipleof 25 KHz/50 KHz.),then, based on the discussion above, the FFT output sequence {Y′₅₀₃^(k)} will move an extra −m_(N) position. If we add −m_(N) as the shiftamount in the future modules (for example, pilot positions and values inslicer/equalizer modules), moving the OFDMA signal back to the originalbaseband location (e.g., the original center frequency of the 96 MHZband) may not be necessary.

FIG. 6 is an OFMDA-only signal, according to some embodiments. Similarto what was discussed in conjunction with FIG. 7, if the OFDMA signal ismoved with additional frequency shift 601, the center of OFDMA signal111 will move to DC position 670. Then one tap of the same coefficientsequence symmetric FIR filter with wider bandwidth (602) can be appliedto remove all mirror signals and out-of-band noise. Similar to FIG. 7,we can get shift −m_(w) for frequency shift 601.

Even though in the processing of FIG. 6 and FIGS. 7, 602 and 652 aredifferent filters, the filters can have the same number of taps andshare the same hardware logic with different coefficients.

FIG. 5 shows an example of combined processing for ATDMA/OFDMA signals,according to some embodiments. First, based on OFDMA active signal range(e.g., 101 in FIGS. 1 and 7, or 111 in FIGS. 2 and 6) and centerfrequency, the receiver calculates the frequency shift FRQ_W 651 orFRQ_N 601 (e.g., to move the center frequency) and oscillator frequencyfor the mixer 501. There are two shift values (SFT_W 653 and SFT_N 603)and two frequencies (FRQ_W 651 and FRQ_N 601), where “W” corresponds tothe wider OFDM filter 602 in FIG. 6, and “N” corresponds to the narrowOFDMA filter 652. Second, based on the bandwidth of the shifted OFDMAsignals (e.g., 611 in FIG. 6 or 631 in FIG. 7, essentially the same as101/111), the receiver uses two low-pass symmetric FIR filterscoefficients (FIR_W 602 and FIR_N 652 in FIG. 5) to remove all ATDMAsignals and out-of-band noise.

Below are two nonlimiting examples of filter coefficients, one for a 20MHz filter, and another for a 65 MHz filter:

20 MHz Filter Coefficients Set {462, 414, −194, −1709, −3800, −5387,−4930, −1155, 6105, 15462, 24263, 29606, 29606, 24263, 15462, 6105,−1155, −4930, −5387, −3800, −1709, −194, 414, 462}65 MHz Filter Coefficients Set{−285, 1640, 2260, −2262, 90, 3852, −5076,−86, 9404, −13632, −237, 72246, 72246, −237, −13632, 9404, −86, −5076,3852, 90, −2262, 2260, 1640, −285};

In some embodiments, the two sets of Filters have the same number oftaps. Switching the coefficients allows the same Filter hardware toprocess a signal at different bandwidths.

In some embodiments, the receiver includes control switches 600A, 600Band 600C (collectively referred to as control switches 600) to changethe working mode from the wide OFDMA filter to/from the narrow OFDMAfilter. For example, when ATDMA signals appear, the bandwidth of OFDMAsignal occupies a narrow bandwidth (e.g., 101 in FIGS. 1 and 7). Thecontrol switches 600 will apply FRQ_N 651, FIR_N 652, and SFT_N 653 tothe system. The oscillator frequency FRQ_N 651 will move the center ofthe OFDMA signal to DC. Narrow band filter FIR_N 652 will remove all thesignals outside the OFMDA signal. After FFT, shift register SFT_N 653will move the FFT output to the original position.

As another example, when OFDMA occupies the ATDMA frequency range, theOFDMA signal occupies a wide bandwidth (e.g., 111 FIGS. 2 and 6). Theswitches 600 will apply FRQ_W 601, FIR_W 602, and SFT_W 603 to thesystem. The oscillator frequency FRQ_W 601 will move the center of theOFDMA signal to DC. Wide band filter FIR_W 602 will remove all thesignals outside the OFMDA signal. After FFT, shift register SFT_W 603will move the FFT output to the original position.

Since there is cyclic-prefix period between each frame for timingalignment, there are samples between each frame that may be dropped ifthe CMTS is able to stabilize the timing with the CM. For example, afterperforming an initial timing offset adjustment, the CMTS may besynchronized such that it receives data at the adjusted timing. In suchexamples, switch 600 can operate during the cyclic-prefix period at eachOFDMA frame boundary on the fly. In some embodiments, the CMTS has ascheduler so that the CM knows how to decode the received signal (e.g.,the CM can be configured frame-by-frame via the CMTS scheduler), and theCM can adjust the type of OFDMA filtering (e.g., using switches 600)similarly on a frame-by-frame basis.

The receiving device, as explained above, can be a cable modem (CM). Insome embodiments, the CM can, for example, use the same dynamic mixerfrequency and change the filter coefficient frame by frame, on the fly.

The subject matter described herein can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structural means disclosed in this specification andstructural equivalents thereof, or in combinations of them. The subjectmatter described herein can be implemented as one or more computerprogram products, such as one or more computer programs tangiblyembodied in an information carrier (e.g., in a machine readable storagedevice), or embodied in a propagated signal, for execution by, or tocontrol the operation of, data processing apparatus (e.g., aprogrammable processor, a computer, or multiple computers). A computerprogram (also known as a program, software, software application, orcode) can be written in any form of programming language, includingcompiled or interpreted languages, and it can be deployed in any form,including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program does not necessarily correspond to a file. A programcan be stored in a portion of a file that holds other programs or data,in a single file dedicated to the program in question, or in multiplecoordinated files (e.g., files that store one or more modules, subprograms, or portions of code). A computer program can be deployed to beexecuted on one computer or on multiple computers at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described in this specification, includingthe method steps of the subject matter described herein, can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions of the subject matter describedherein by operating on input data and generating output. The processesand logic flows can also be performed by, and apparatus of the subjectmatter described herein can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processor of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. Information carrierssuitable for embodying computer program instructions and data includeall forms of nonvolatile memory, including by way of examplesemiconductor memory devices, (e.g., EPROM, EEPROM, and flash memorydevices); magnetic disks, (e.g., internal hard disks or removabledisks); magneto optical disks; and optical disks (e.g., CD and DVDdisks). The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, the subject matter describedherein can be implemented on a computer having a display device, e.g., aCRT (cathode ray tube) or LCD (liquid crystal display) monitor, fordisplaying information to the user and a keyboard and a pointing device,(e.g., a mouse or a trackball), by which the user can provide input tothe computer. Other kinds of devices can be used to provide forinteraction with a user as well. For example, feedback provided to theuser can be any form of sensory feedback, (e.g., visual feedback,auditory feedback, or tactile feedback), and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The subject matter described herein can be implemented in a computingsystem that includes a back end component (e.g., a data server), amiddleware component (e.g., an application server), or a front endcomponent (e.g., a client computer having a graphical user interface ora web browser through which a user can interact with an implementationof the subject matter described herein), or any combination of such backend, middleware, and front end components. The components of the systemcan be interconnected by any form or medium of digital datacommunication, e.g., a communication network. Examples of communicationnetworks include a local area network (“LAN”) and a wide area network(“WAN”), e.g., the Internet.

It is to be understood that the disclosed subject matter is not limitedin its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The disclosed subject matter is capable ofother embodiments and of being practiced and carried out in variousways. Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods, and systems for carryingout the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimswhich follow.

1. A decoding method for decoding modulated data, the method comprising:receiving a modulated signal; determining a format of the modulatedsignal, wherein the format comprises either: a first format comprising afirst type of modulated signal; or a second format comprising the firsttype of modulated signal and a second type of modulated signal that isdifferent than the first type; and decoding the modulated signal,comprising: determining a frequency shift amount based on the format ofthe modulated signal; shifting a frequency band of the first type ofmodulated signal from an original position to a shifted position,thereby shifting a center frequency of the first type of modulatedsignal by the frequency shift amount; and filtering, based on the formatof the modulated signal, signals outside of the frequency band of theshifted first type of modulated signal.
 2. The method of claim 1,wherein filtering comprises: determining a set of filtering coefficientsfor the modulated signal based on whether the modulated signal comprisesthe first format or the second format; and filtering the modulatedsignal using the set of filtering coefficients.
 3. The decoding methodof claim 1, further comprising: transforming the shifted first type ofmodulated signal from the frequency domain; equalizing the transformedfirst type of modulated signal to generate an equalized signal; andshifting the equalized signal back to the original position.
 4. Thedecoding method of claim 1, wherein: the first type of signal comprisesan Orthogonal Frequency-Division Multiple Access (OFDMA) signal; and thesecond type of data comprises Advanced Time Division Multiple Access(ATDMA) signal.
 5. The method of claim 1, wherein determining whetherthe modulated signal comprises the first format or the second formatcomprises: receiving scheduling information from a scheduler; anddetermining, using the scheduling information, whether the modulatedsignal comprises the first format or the second format.
 6. The method ofclaim 1, wherein the modulated signal is received on a frame-by-framebasis, and decoding the modulated signal comprises: determining, foreach frame, whether the frame comprises the first format or the secondformat; and decoding each frame based on the determination, therebyallowing each frame dynamically change between the first format and thesecond format.
 7. An apparatus for decoding modulated data, theapparatus comprising: a receiver configured to receive a modulatedsignal; a decoder comprising a mixer and a filter, wherein the decoderis configured to: determine a format of the modulated signal, whereinthe format comprises either: a first format comprising a first type ofmodulated signal; or a second format comprising the first type ofmodulated signal and a second type of modulated signal that is differentthan the first type; and decode the modulated signal, comprising:determining a frequency shift amount based on the format of themodulated signal; shifting, using a mixer, a frequency band of the firsttype of modulated signal from an original position to a shiftedposition, thereby shifting a center frequency of the first type ofmodulated signal by the frequency shift amount; and filtering, using afilter that takes into account the format of the modulated signal,signals outside of the frequency band of the shifted first type ofmodulated signal.
 8. The apparatus of claim 7, wherein the decoder isconfigured to perform the filtering by: determining a set of filteringcoefficients for the modulated signal based on whether the modulatedsignal comprises the first format or the second format; and filtering,using the filter, the modulated signal using the set of filteringcoefficients.
 9. The apparatus of claim 7, wherein the decoder furthercomprises: a fast Fourier transform (FFT) module configured to transformthe shifted first type of modulated signal from the frequency domain; anequalizer in communication with the FFT module, configured to equalizethe transformed first type of modulated signal to generate an equalizedsignal; and a shift register in communication with the equalizerconfigured to shift the equalized signal back to the original position.10. The apparatus of claim 7, wherein: the first type of signalcomprises an Orthogonal Frequency-Division Multiple Access (OFDMA)signal; and the second type of data comprises Advanced Time DivisionMultiple Access (ATDMA) signal.
 11. The apparatus of claim 7, whereinthe receiver is configured to determine whether the modulated signalcomprises the first format or the second format by: receiving schedulinginformation from a scheduler; and determining, using the schedulinginformation, whether the modulated signal comprises the first format orthe second format.
 12. The apparatus of claim 7, wherein: the receiverreceives the modulated signal on a frame-by-frame basis; and the decoderis configured to decode the modulated signal by determining, for eachframe, whether the frame comprises the first format or the secondformat; and decoding each frame based on the determination, therebyallowing each frame dynamically change between the first format and thesecond format.